Responsible fitness instructors won't promise that you'll burn a certain number of calories when you do their workouts -- and for very good reason. The number of calories you'll burn during any given workout depends on too many factors to promise a set number. That's probably why the Denise Austin "Utimate Fat Burner" exercise DVD doesn't include an estimate of the number of calories you'll burn, but you do have ways to arrive at a rough estimate.
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About the Program
In a very general sense, the Denise Austin Ultimate Fat Burner workout is a high-intensity, high-impact aerobics class. The DVD is a 45-minute workout that that includes bouts of high-intensity kickboxing, step aerobics and moves that mimic those you might do in basketball, skiing and skating. There are also slower periods during which you'll do core training exercises, so in that sense, the DVD is also an interval workout. Throughout the workout, Austin provides three different levels of intensity, allowing people of varying levels of physical fitness to choose the moves that work best for them.
Factors Affecting Calories
Several factors play into how many calories you can burn during any given activity. Perhaps the most clear-cut is weight. A person who weighs 125 pounds can expect to burn roughly 210 calories during a 30-minute session of high-intensity aerobics, while a 185-pound person may burn about 311 calories during the same session. Age and gender also are factors. Among men and women of the same age and weight, men usually have more muscle than women, an because muscle burns calories more efficiently than fat they'll tend to burn more calories. As you age, you tend to burn fewer calories. And of course, the intensity at which you do any workout also matters. If you choose the higher-intensity step moves featured in the DVD instead of the lower-intensity ones, you're likely to burn more calories.
Track Your Heart Rate
You can expect to burn roughly 315 calories per session of most high-impact aerobics classes if you weigh about 125 pounds, and more like 466 calories per session if you' weigh 185 pounds. Those, however, are only rough estimates. For a closer count wear a heart rate monitor and check your heart rate three times -- about every 10 minutes after the first five minutes of your workout. Then add the three heart rates and divide the total by three to determine your average heart rate for the session. The harder your heart is pumping, the more calories you'll be burning.
The Heart Rate Formula
Once you have determined your average heart rate, use an online "calories burned" calculator to determine how many calories you're burning based on heart rate. For example, if you're a 30-year-old woman who weighs 125 pounds and your average heart rate during exercise is 90 beats per minute, you could expect to burn 3.5 calories per minute. With a heart rate went of 110 beats per minute, you'd burn about 5.7 calories per minute. These calculators can be handy to keep track of a general calorie burn for each workout, but even they provide only an estimate.